Motor power controller for a disk drive, disk drive comprising a motor power controller and method for controlling the motor power of a disk drive

ABSTRACT

A motor power controller for a disk drive includes at least two operation states. In a first operation state, the disk drive motor is running continuously, and in a second operation state, the motor is spun up at the beginning of each data operation and spun down at the end of each data operation. The motor power controller transitions the disk drive from the first to the second operation state when a time interval is longer than a predetermined period of time without any data requests is determined. Further, the motor power controller transitions the disk drive from the second to the first operation state when a predetermined number of time intervals between consecutive data requests are all smaller than the predetermined period of time.

The present invention relates to a motor power controller for a diskdrive. Further on, the present invention relates to a disk drivecomprising a motor power controller and to a method for controlling themotor power of a disk drive.

For the following description, a disk drive shall be defined as anoptical drive like a CD-ROM drive or a magnetic drive like a diskettedrive or a magneto-optical drive.

Portable computers like laptop computers or portable audio/video systemslike DVD players or other portable devices operate usually on batterypower. The duration at which e.g. a portable device operates before itsbattery must be recharged is governed by the level of current which isdrawn from the battery, and the total charge the battery is capable ofstoring. In order to provide a portable device which operates for a longtime period before its battery must be recharged, development effortshave focused both on maximizing the total charge carried by such abattery, and on minimizing the current drawn from the battery or onminimizing power consumption by the portable device.

As more and more efficient logic and displays become available, animportant factor in determining battery life is the disk drive of theportable device. For that, in order to maximize battery life-time, theefficiency of the disk drive has to be improved.

The U.S. Pat. No. 5,517,649 discloses an adaptive power management forhard disk drives. In this prior art document there is described a methodof managing the power consumed by a hard disk drive, whereby in a firststep the work load placed on the hard disk drive is measured. The nextstep is to determine the average power consumed in the disk drive in theactive state and in a lower power state for a series of wait times.Then, the total average power consumed by the disk drive for both statesfor a series of wait times is determined. The next step is to determinethe wait time at which the total average power consumed by the diskdrive is minimum. The final step is to set the wait time at which thedisk drive operates to the previously determined minimum wait time.

The U.S. Pat. No. 5,493,670 discloses a method for managing the powerconsumed by a disk drive in a portable laptop computer. According to theU.S. Pat. No. 5,493,670 the power in a laptop computer is conserved byspinning down the disk immediately when there is inactivity if the nextaccess will likely occur more than a number of seconds in the future,for example the next access will likely occur far enough in the futurefor the system to save power by spinning down the disk. According to themethod described in this prior art document, the power system spins downa hard disk drive when it has not been accessed after a predeterminedlength of time. A decision to spin down the disk is made by a computerin response to the past history of the disk activity. The past historyof disk activity is also used to adjust the threshold.

Other methods for controlling power consumption of a disk drive in aportable computer are disclosed in the U.S. Pat. No. 6,097,679 and inthe International PCT Patent Application WO 01/15161 A1.

The present invention provides a motor power controller for a diskdrive, especially for a disk drive of a portable device, comprisingmeans defining at least two operation states of said disk drive, a firstoperation state running a motor of said disk drive continuously, and asecond operation state spinning said motor up at the beginning of eachdata operation and spinning said motor down at the end of each dataoperation; comprising means transitioning said disk drive from saidfirst operation state to said second operation state when a timeinterval being longer than a predetermined period of time without anydata requests is determined; further comprising means transitioning saiddisk drive from said second operation state to said first operationstate when a predetermined number of time intervals between consecutivedata requests are determined all or each of them being smaller than saidpredetermined period of time.

The motor power controller according to the present invention minimizesthe motor energy consumption of the disk drive while the disk driveneeds no information or knowledge about the application running, thebuffer size or the data request patterns of the portable device to whichthe disk drive is connected or which the disk drive is part of. Themotor power controller according to the present invention is simple anddoes not increase communications between the disk drive and the portabledevice or application running thereon.

In accordance with a preferred embodiment of the invention the motorpower controller comprises means calculating said predetermined periodof time from an energy consumption and/or a power consumption of saiddisk drive.

FIG. 1 shows a state diagram of disk drive motor controller according tothe present invention;

FIG. 2 shows a diagram illustrating the power and energy consumption ofthe disk drive during the first operation state which is also called“continuous-state”; and

FIG. 3 shows a diagram illustrating the power and energy consumption ofthe disk drive during the second operation state which is also called“spin up/down-state”.

The present invention relates to a motor power controller for a diskdrive, especially for a portable optical drive.

According to the present invention, the motor power controller comprisesmeans defining at least two operation states of said disk drive. FIG. 1shows a so-called state diagram of the disk drive motor controllershowing two operational states, namely a first operation state 10 and asecond operation state 11. In the first operation state 10 a motor ofsaid disk drive is running continuously also during the time when nodata operation is being carried out. The time when no data operation isbeing carried out is hereinafter called buffer phase. During said secondoperation state 11 the motor spins up at the beginning of each dataoperation, namely each read and/or write operation, and spins down atthe end of each read and/or write operation. During this secondoperation state 11 the disk drive motor is not running during the bufferphase. The first operation state 10 is also called “continuous-state”and the second operation state 11 is also called “spin up/down-state” or“default-state”.

It should be noted, that the spinning-down of said motor at the end ofeach data operation during the second operation state 11 can beperformed passively or actively. The phrase “spinning said motor down”is not directed to only one of these two options. The phrase “spinningsaid motor down” has to be understood in a way that both options fallwithin the scope of this phrase.

The motor power controller according to the present invention comprisesmeans transitioning the disk drive from the first operation state 10 tothe second operation state 11 and from the second operation state 11 tothe first operation state 10. The arrow 12 in FIG. 1 illustrates thetransition from the first operation state 10 to the second operationstate 11. The arrow 13 in FIG. 1 illustrates the transition from thesecond operation state 11 to the first operation state 10.

According to the present invention, the transition from the firstoperation state 10—the so-called “continuous-state”—to the secondoperation state 11—the so-called “spin up/down-state”—takes place, whena time interval longer or larger than a predetermined period of time isdetermined, without any read and/or write requests occurring during thistime interval. This indicates that the portable device, especially theapplication running thereon, has stopped streaming or that more bufferspace has become available. With increasing buffer space the bufferphase increases. Under this condition it is more efficient to allow amotor of a disk drive to stop during the buffer phase and to spin upagain before the next read and/or write operation.

The transition from the second operation state 11—the so-called “spinup/down-state”—to the first operation state 10—the so-called“continuous-state”—takes place when a predetermined number a of timeintervals between consecutive data requests are determined all beingsmaller than said predetermined period of time. This indicates that anapplication with a small buffer size is streaming data to and/or fromthe disk drive. As more data requests at roughly the same interval canbe expected during streaming, it is more energy efficient to have themotor running continuously during the buffer phase.

In the most simple embodiment the predetermined number of time intervalsbetween consecutive data requests could be chosen as α=1. However, it ismore efficient and reliable to choose α=3. When α=3 is chosen, thetransition from the second operation state 11—the so-called “spinup/down-state”—to the first operation state 10—the so-called“continuous-state”—takes only place when three consecutive timeintervals between consecutive data requests are determined, whereby eachof the three time intervals has to be smaller than said predeterminedperiod of time. In case only two of the three time intervals would besmaller than said predetermined period, the transition would not takeplace.

The present invention provides a very simple solution for minimizing thepower consumption in a portable or none-portable disk drive withoutincreasing communications between the disk drive and the portable deviceor the application running thereon.

Preferably, the motor power controller comprises means calculating saidpredetermined period of time which is used as criteria for thetransitioning processes from the energy consumption and the powerconsumption of the disk drive motor. The invention therefore needs noinformation about the portable device or the application runningthereon.

When the phrase “motor” is used in connection with energy or powerconsumption, it should be noted this could relate to the energy or powerconsumption of the motor itself and/or the energy or power consumptionof a motor driver and/or the energy or power consumption of motor drivercontrol circuits.

For a drive running in a so-called CLV (constant linear velocity) mode,the bit rate during a read and/or write operation is not dependent onthe radius of the disk, because of the fact that the motor rotationfrequency or motor rotation speed increases with decreasing disk radius.For a drive running in said CLV mode, the predetermined period of timeis calculated from the energy consumption of said drive used forspinning up the disk drive motor and from the power consumption of thedisk drive motor during continuous operation of said disk drive, usingthe following formula:

${t_{CLV} = {\frac{E_{{spin}\text{-}{up}}(r)}{P_{continuous}(r)} + t_{active}}};$wherein

t_(CLV) is the predetermined period of time for a disk drive operated inthe CLV mode;

E_(spin-up) is the energy consumption of said disk drive used forspinning the disk drive motor up;

P_(continuous) is power consumption of said disk drive motor used forspinning the disk when the disk drive is in continuous operation, alsoduring the buffer phase;

r is the disk radius;

and wherein

t_(active) is the time at which said disk drive is active during a dataoperation.

For a disk drive operated in the CLV mode E_(spin-up) and P_(continuous)are a function of the disk radius r. The time t_(active) is a constantfor a disk drive operated in the CLV mode, wherebyt _(active) =t _(initialize) +t _(search) +t _(read/write)meaning that t_(active) can be calculated from the time t_(initialize)used to initialize the optics of the disk drive, from the timet_(search) used for search operations and from the time t_(read/write)used for read and write operations. It is also possible, that t_(active)is only a function of t_(read/write) for applications for which nosearch and initialization operations are necessary.

For a drive running in a so-called CAV (constant angular velocity) modethe bit rate during a read and/or write operation is dependent on theradius of the disk and the predetermined period of time is calculatedfrom the energy consumption of said drive used for spinning up the diskdrive motor and from the power consumption of the disk drive motorduring continuous operation of said disk drive, using the followingformula:

${t_{CAV} = {\frac{E_{{spin}\text{-}{up}}}{P_{continuous}} + {t_{active}(r)}}};$wherein

t_(CAV) is the predetermined period of time for a disk drive operated inthe CAV mode.

For a disk drive operated in the CAV mode E_(spin-up) and P_(continuous)are constant. The time t_(active) is a function of the disk radius r, ast_(read/write) is a function of the disk radius r, for a given amount ofdata to be accessed. For a disk drive operated in the CAV modet_(active) can be calculated as follows:t _(active)(r)=t _(initialize) +t _(search) +t _(read/write)(r)

For applications for which no search and initialization operations arenecessary, t_(active)(r) is only a function of t_(read/write)(r).

In the CLV and the CAV mode, the radius of the last access to the diskdrive can be used for the calculation of the predetermined period oftime t_(CLV) or t_(CAV). The best result can be achieved whenconsecutive data request are for data from about the same radius, e.g.when streaming a large contiguous file.

FIG. 2 shows a diagram illustrating the power consumption P of the diskdrive over the time t during the first operation state 10, FIG. 3 showsa diagram illustrating the power consumption P of the disk drive duringthe second operation state 11. The power or energy consumption duringt_(active) is for both operations states the same. For the firstoperation state 10 (“continuous-state”, see FIG. 2) the energyconsumption E_(continuous) used by the motor during buffer phase in thecontinuous mode is illustrated by a hatched rectangle. The duration ofbuffer phase is characterized by the time t_(buffer), whereby:E _(continuous) =P _(continuous) *t _(buffer)

For the second operation state 11 “spin up/down-state”, see FIG. 3) theenergy consumption E_(spin-up) of the motor is also illustrated by ahatched rectangle. The duration of the spin-up phase of the motor ischaracterized by the time t_(spin-up) whereby:E _(spin-up) =P _(spin-up) *t _(spin-up).

The predetermined period of time t_(CLV) or t_(CAV) used as criteria forthe transitioning of the disk drive from the first operation state 10 tothe second operation state 11 and from the second operation state 11 tothe first operation state 10 is chosen in a way that the energyconsumption E_(continuous) and the energy consumption E_(spin-up)illustrated by the hatched rectangles in FIGS. 2 and 3 are equal.

The above described motor power controller and method is preferably partof a drive, especially of a portable optical disk drive.

The present invention can be used in all devices incorporating a diskdrive, especially an optical disk drive, e.g. in audio/video systems, inlaptop computers and the like.

1. A motor power controller for a disk drive comprising: means fordefining at least two operation states of said disk drive, a firstoperation state running a motor of said disk drive continuously, and asecond operation state spinning said motor up at a beginning of eachdata operation and spinning said motor down at an end of the each dataoperation; means for transitioning said disk drive from said firstoperation state to said second operation state when a time intervalbeing longer than a predetermined period of time without any datarequests is determined; and means for transitioning said disk drive fromsaid second operation state to said first operation state when apredetermined number of time intervals between consecutive data requestsare determined all or each of them being smaller than said predeterminedperiod of time.
 2. The motor power controller according to claim 1,further comprising calculating means for calculating said predeterminedperiod of time from an energy consumption and/or a power consumption ofsaid disk drive.
 3. A motor power controller for a disk drivecomprising: means for defining at least two operation states of saiddisk drive, a first operation state running a motor of said disk drivecontinuously, and a second operation state spinning said motor up at abeginning of each data operation and spinning said motor down at an endof the each data operation; means for transitioning said disk drive fromsaid first operation state to said second operation state when a timeinterval being longer than a predetermined period of time without anydata requests is determined; means for transitioning said disk drivefrom said second operation state to said first operation state when apredetermined number of time intervals between consecutive data requestsare determined all or each of them being smaller than said predeterminedperiod of time; and calculating means calculate for calculating saidpredetermined period of time from an energy consumption of said diskdrive used for spinning said disk drive motor up and from a powerconsumption of said disk drive motor during continuous operation of saiddisk drive.
 4. A motor power controller for a disk drive comprising:means for defining at least two operation states of said disk drive, afirst operation state running a motor of said disk drive continuously,and a second operation state spinning said motor up at a beginning ofeach data operation and spinning said motor down at an end of the eachdata operation; means for transitioning said disk drive from said firstoperation state to said second operation state when a time intervalbeing longer than a predetermined period of time without any datarequests is determined; means for transitioning said disk drive fromsaid second operation state to said first operation state when apredetermined number of time intervals between consecutive data requestsare determined all or each of them being smaller than said predeterminedperiod of time; and calculating means for calculating said predeterminedperiod of time; wherein the disk drive is operated at a CLV (ConstantLinear Velocity) mode, and wherein said calculating means calculate saidpredetermined period of time using the following formula:${t_{CLV} = {\frac{E_{{spin}\text{-}{up}}(r)}{P_{continuous}(r)} + t_{active}}};$wherein t_(CLV) is the predetermined period of time; E_(spin-up) is theenergy consumption of said disk drive used for spinning the disk drivemotor up; P_(continuous) is power consumption of said disk drive motorused for spinning the disk when the disk drive is in continuousoperation, also during the buffer phase; t_(active) is the time at whichsaid disk drive is active during a data operation; r is the disk radius.5. A motor power controller for a disk drive comprising: means fordefining at least two operation states of said disk drive, a firstoperation state running a motor of said disk drive continuously, and asecond operation state spinning said motor up at a beginning of eachdata operation and spinning said motor down at an end of the each dataoperation; means for transitioning said disk drive from said firstoperation state to said second operation state when a time intervalbeing longer than a predetermined period of time without any datarequests is determined; means for transitioning said disk drive fromsaid second operation state to said first operation state when apredetermined number of time intervals between consecutive data requestsare determined all or each of them being smaller than said predeterminedperiod of time; and calculating means for calculating said predeterminedperiod of time; wherein the disk drive is operated at a CAV (ConstantAngular Velocity) mode, and wherein said calculating means calculatesaid predetermined period of time using the following formula:${t_{CAV} = {\frac{E_{{spin}\text{-}{up}}}{P_{continuous}} + {t_{active}(r)}}};$wherein t_(CAV) is the predetermined period of time; E_(spin-up) is theenergy consumption of said disk drive used for spinning the disk drivemotor up; P_(continuous) is power consumption of said disk drive motorused for spinning the disk when the disk drive is in continuousoperation, also during the buffer phase; t_(active) is the time at whichsaid disk drive is active during a data operation; r is the disk radius.6. The motor power controller according to claim 1, wherein said dataoperations are read and/or write operations.
 7. A disk drive comprisingincluding a motor power controller, said motor power controllercomprising: means for defining at least two operation states of saiddisk drive, a first operation state running a motor of said disk drivecontinuously, and a second operation state spinning said motor up at abeginning of each data operation and spinning said motor down at an endof the each data operation; means for transitioning said disk drive fromsaid first operation state to said second operation state when a timeinterval being longer than a predetermined period of time without anydata requests is determined; and means for transitioning said disk drivefrom said second operation state to said first operation state when apredetermined number of time intervals between consecutive data requestsare determined all or each of them being smaller than said predeterminedperiod of time.
 8. The disk drive according to claim 7, furthercomprising calculating means for calculating said predetermined periodof time from an energy consumption and/or a power consumption of saiddisk drive.
 9. A disk drive including a motor power controller, saidmotor power controller comprising: means for defining at least twooperation states of said disk drive, a first operation state running amotor of said disk drive continuously, and a second operation statespinning said motor up at a beginning of each data operation andspinning said motor down at an end of the each data operation; means fortransitioning said disk drive from said first operation state to saidsecond operation state when a time interval being longer than apredetermined period of time without any data requests is determined;means for transitioning said disk drive from said second operation stateto said first operation state when a predetermined number of timeintervals between consecutive data requests are determined all or eachof them being smaller than said predetermined period of time; andcalculating means for calculating said predetermined period of time froman energy consumption of said disk drive used for spinning said diskdrive motor up and from a power consumption of said disk drive motorduring continuous operation of said disk drive.
 10. A method forcontrolling a motor power of a drive comprising the acts of: defining atleast two operation states of said disk drive, a first operation staterunning a motor of said disk drive continuously, and a second operationstate spinning said motor up at a beginning of each data operation andspinning said motor down at an end of each data operation; transitioningsaid disk drive from said first operation state to said second operationstate when a time interval being longer than a predetermined period oftime without any data requests is determined; and transitioning saiddisk drive from said second operation state to said first operationstate when a predetermined number of time intervals between consecutivedata requests are determined all or each of them being smaller than saidpredetermined period of time.
 11. The method according to claim 10,further comprising the act of calculating said predetermined period oftime from an energy consumption and/or a power consumption of said diskdrive.
 12. A method for controlling a motor power of a disk drivecomprising the acts of: defining at least two operation states of saiddisk drive, a first operation state running a motor of said disk drivecontinuously, and a second operation state spinning said motor up at abeginning of each data operation and spinning said motor down at an endof each data operation; transitioning said disk drive from said firstoperation state to said second operation state when a time intervalbeing longer than a predetermined period of time without any datarequests is determined; transitioning said disk drive from said secondoperation state to said first operation state when a predeterminednumber of time intervals between consecutive data requests aredetermined all or each of them being smaller than said predeterminedperiod of time; and calculating said predetermined period of time froman energy consumption of said disk drive used for spinning said diskdrive motor up and from a power consumption of said disk drive motorduring continuous operation of said disk drive.
 13. A method forcontrolling a motor power of a disk drive comprising the acts of:defining at least two operation states of said disk drive, a firstoperation state running a motor of said disk drive continuously, and asecond operation state spinning said motor up at a beginning of eachdata operation and spinning said motor down at an end of each dataoperation; transitioning said disk drive from said first operation stateto said second operation state when a time interval being longer than apredetermined period of time without any data requests is determined;transitioning said disk drive from said second operation state to saidfirst operation state when a predetermined number of time intervalsbetween consecutive data requests are determined all or each of thembeing smaller than said predetermined period of time; operating the diskdrive at a CLV (Constant Linear Velocity) mode; and calculating saidpredetermined period of time using the following formula:${t_{CLV} = {\frac{E_{{spin}\text{-}{up}}(r)}{P_{continuous}(r)} + t_{active}}};$wherein t_(CLV) is the predetermined period of time; E_(spin-up) is theenergy consumption of said disk drive used for spinning the disk drivemotor up; P_(continuous) is power consumption of said disk drive motorused for spinning the disk when the disk drive is in continuousoperation, also during the buffer phase; t_(active) is the time at whichsaid disk drive is active during a data operation; r is the disk radius.14. A method for controlling a motor power of a disk drive comprisingthe acts of: defining at least two operation states of said disk drive,a first operation state running a motor of said disk drive continuously,and a second operation state spinning said motor up at a beginning ofeach data operation and spinning said motor down at an end of each dataoperation; transitioning said disk drive from said first operation stateto said second operation state when a time interval being longer than apredetermined period of time without any data requests is determined;transitioning said disk drive from said second operation state to saidfirst operation state when a predetermined number of time intervalsbetween consecutive data requests are determined all or each of thembeing smaller than said predetermined period of time; operating the diskdrive at a CAV (Constant Angular Velocity) mode; and calculating saidpredetermined period of time using the following formula:${t_{CAV} = {\frac{E_{{spin}\text{-}{up}}}{P_{continuous}} + {t_{active}(r)}}};$wherein t_(CAV) is the predetermined period of time; E_(spin-up) is theenergy consumption of said disk drive used for spinning the disk drivemotor up; P_(continuous) is power consumption of said disk drive motorused for spinning the disk when the disk drive is in continuousoperation, also during the buffer phase; t_(active) is the time at whichsaid disk drive is active during a data operation; r is the disk radius.15. The method according to claim 10, wherein said data operations areread and/or write operations.
 16. A controller for a disk drive, whereinthe controller is configure to: define at least two operation states ofsaid disk drive, a first operation state running a motor of said diskdrive continuously, and a second operation state spinning said motor upat a beginning of each data operation and spinning said motor down at anend of the each data operation; transition said disk drive from saidfirst operation state to said second operation state when a timeinterval being longer than a predetermined period of time without anydata requests is determined; transition said disk drive from said secondoperation state to said first operation state when a predeterminednumber of time intervals between consecutive data requests aredetermined all or each of them being smaller than said predeterminedperiod of time; and calculate said predetermined period of time from anenergy consumption of said disk drive used for spinning said disk drivemotor up and from a power consumption of said disk drive motor duringcontinuous operation of said disk drive.